Based on the US data, Peru is now the biggest cocaine producer in the region, a reputation it held in the 1980s and 1990s, before Colombia rose to drug producing and trafficking notoriety. This latest role reversal might imply something of a “balloon” effect, where production is quashed in one country, only to have cultivation and production pop up with more force next door.

A numbers game?

In its annual report, the UN Office on Drugs and Crime – the only other body that measures cocaine production in the Andes Mountains – said Colombian cocaine production remained stable in 2011 and coca cultivation actually rose that same year, by 3 percent.

The UN estimate for 2011 cocaine production was 345 tons compared to the US estimate of 195 tons – a discrepancy of 77 percent. UN and US cocaine figures have always differed slightly, but have tended to track each other. No longer, it seems.

But beyond Colombia’s potential progress under the US numbers, perhaps even more surprising are Bolivia and Peru’s apparent leaps ahead of their neighbor in how much cocaine they are able to produce from the coca leaf.

The last time coca cultivation was measured by both the UN and the US, in 2010, Colombia and Peru had about the same number of coca fields, whereas Bolivia had less than half. According to the US, Colombian drug producers are now producing less than half the amount of cocaine from their coca leaves than their counterparts in Bolivia and Peru. Though Michael McKinley, the US ambassador to Colombia, told El Tiempo the White House figures have “95 percent” accuracy, the US has declined to make its methodology public.

This discrepancy between the amount of coca leaf versus the amount of cocaine produced is interesting when taking into account a key factor in previous US calculations: What amounts of coca leaves are grown in Peru and Bolivia for chewing and products like coca tea?

A State Department report earlier this year said it was US government policy to overestimate cocaine production figures for Peru and Bolivia “to some unknown extent," because it was difficult to say with certainty what coca was being funneled towards legal versus illegal markets in those two countries.

‘You can see the results’ in Colombia

In a statement accompanying Kerlikowske’s speech, the US office pointed to what they believed was behind Colombia’s strides in combating cocaine production: Plan Colombia, which has strengthened the US-Colombia partnership. “These reductions can be traced to a variety of factors that resulted from the strengthened US-Colombia partnership forged through Plan Colombia.”

Since 2000, the US has spent $8 billion on Plan Colombia, a program to combat drugs and leftist insurgents in the Andean nation. It is the largest US foreign aid program outside the Middle East and Afghanistan and has helped bring about major improvements in Colombian security, though has come under criticism for failing to protect human rights.

Fredy Alonso Hurtado, a middle-aged doorman in Medellín – Colombia’s second-largest city and once the heart of the country’s cocaine empire – agreed that US investment had made a major difference. “Even in my barrio [neighborhood], you can see the results of Plan Colombia,” he says. “There are new roads, a school, a recreation center – these things help steer people away from drug trafficking.”

According to Mr. Hurtado, Colombia produced less cocaine than Bolivia even though it grows more coca because since the beginning of Plan Colombia, measures countering cocaine production and transportation have been much stricter “at every level.”

The UN doesn’t seem agree to with the US on that front either, estimating that cocaine yield from coca is around the same level for all three countries.

"While we don't challenge the UN estimates, we believe that our estimates are informed by more sophisticated technology and a different methodology," said the US office.

As the US refrains from explaining its methodology, it is leaving itself “wide open to charges that its estimates are politicized,” says the Washington Office on Latin America's Adam Isacson.

Plan Colombia hasn’t just helped reduce narcotrafficking – it has also strongly advanced American business interests. Colombia is the US’s poster child in the region, and it is strongly in American interests to hail the success of Plan Colombia, so the logic goes.

Bolivia, on the other hand, has consistently put itself at odds with US foreign policy, especially regarding counter-narcotics. Its leftist president Evo Morales, a former coca growers union leader, has fought for the rights of farmers, going so far as to kick out the US Drugs Enforcement Agency in 2008 and refusing to let it back in since. [See the Monitor’s latest cover story on Latin America reinventing the war on drugs]

“When your numbers so plainly appear to favor an ally over an adversary with roughly half as much coca, it's incumbent upon the US to be more transparent about how it derives its estimates,” says Mr. Isacson.